avr32: pm: Fix section mismatch

The power management has a section mismatch which leads to the following
warning during compilation:

WARNING: arch/avr32/mach-at32ap/built-in.o(.text+0x16d4): Section
mismatch in reference from the function avr32_pm_offset() to the
function .init.text:pm_exception()
The function avr32_pm_offset() references
the function __init pm_exception().
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Hans-Christian Egtvedt <hegtvedt@cisco.com>

arch/avr32/mach-at32ap/pm.c

@@ -181,7 +181,7 @@ static const struct platform_suspend_ops avr32_pm_ops = {
 	.enter	= avr32_pm_enter,
 };
 
-static unsigned long avr32_pm_offset(void *symbol)
+static unsigned long __init avr32_pm_offset(void *symbol)
 {
 	extern u8 pm_exception[];